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NetEvaluationMode

[Experimental]

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is an option that can be given when applying neural net functions to input data, specifying whether the net should use training-specific behavior.

Details

  • When a net is applied to an input, net[input,NetEvaluationMode->spec] specifies how layers such as DropoutLayer within the net should behave.
  • With the setting NetEvaluationMode->"Test", the normal behavior of layers like DropoutLayer will be used.
  • With the setting NetEvaluationMode->"Train", the training-specific behavior of layers like DropoutLayer will be used.
  • Recurrent layers such as LongShortTermMemoryLayer also have training-specific behavior via the "Dropout" option.
  • Training a net with NetTrain[net,…] will automatically use training-specific behavior.

Examples

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Basic Examples  (2)Summary of the most common use cases

Normally, training layers like DropoutLayer act like the identity. Create a dropout layer and apply it to an input:

In[1]:=1
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https://wolfram.com/xid/0c0rhshlwdek4-m8xhmo
Out[1]=1
In[2]:=2
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https://wolfram.com/xid/0c0rhshlwdek4-un467n
Out[2]=2

Apply the dropout layer with its training behavior, in which roughly half of the vector components are set to zero and the other half are doubled:

In[3]:=3
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https://wolfram.com/xid/0c0rhshlwdek4-usw7a9
Out[3]=3

Create an ImageAugmentationLayer that takes an image of size 128×128 and returns an image crop of size 64×64:

In[1]:=1
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https://wolfram.com/xid/0c0rhshlwdek4-cz9q25
Out[1]=1

Apply the layer to an image, obtaining the center crop:

In[2]:=2
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https://wolfram.com/xid/0c0rhshlwdek4-w8pza0
Out[2]=2

Apply the layer to an image, specifying that training behavior be used. A random crop will be made and the image will be reflected with the given probabilities:

In[3]:=3
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https://wolfram.com/xid/0c0rhshlwdek4-djcxfj
Out[3]=3

Possible Issues  (1)Common pitfalls and unexpected behavior

Currently, any randomness invoked by NetEvaluationMode->"Train" is not affected by SeedRandom and BlockRandom:

In[1]:=1
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https://wolfram.com/xid/0c0rhshlwdek4-c9zqq8
Out[1]=1
In[2]:=2
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https://wolfram.com/xid/0c0rhshlwdek4-oouzin
Out[2]=2
In[3]:=3
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https://wolfram.com/xid/0c0rhshlwdek4-wzmtxu
Out[3]=3
Wolfram Research (2017), NetEvaluationMode, Wolfram Language function, https://reference.wolfram.com/language/ref/NetEvaluationMode.html.
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Wolfram Research (2017), NetEvaluationMode, Wolfram Language function, https://reference.wolfram.com/language/ref/NetEvaluationMode.html.

Text

Wolfram Research (2017), NetEvaluationMode, Wolfram Language function, https://reference.wolfram.com/language/ref/NetEvaluationMode.html.

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Wolfram Research (2017), NetEvaluationMode, Wolfram Language function, https://reference.wolfram.com/language/ref/NetEvaluationMode.html.

CMS

Wolfram Language. 2017. "NetEvaluationMode." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/NetEvaluationMode.html.

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Wolfram Language. 2017. "NetEvaluationMode." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/NetEvaluationMode.html.

APA

Wolfram Language. (2017). NetEvaluationMode. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/NetEvaluationMode.html

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Wolfram Language. (2017). NetEvaluationMode. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/NetEvaluationMode.html

BibTeX

@misc{reference.wolfram_2025_netevaluationmode, author="Wolfram Research", title="{NetEvaluationMode}", year="2017", howpublished="\url{https://reference.wolfram.com/language/ref/NetEvaluationMode.html}", note=[Accessed: 05-May-2025 ]}

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@misc{reference.wolfram_2025_netevaluationmode, author="Wolfram Research", title="{NetEvaluationMode}", year="2017", howpublished="\url{https://reference.wolfram.com/language/ref/NetEvaluationMode.html}", note=[Accessed: 05-May-2025 ]}

BibLaTeX

@online{reference.wolfram_2025_netevaluationmode, organization={Wolfram Research}, title={NetEvaluationMode}, year={2017}, url={https://reference.wolfram.com/language/ref/NetEvaluationMode.html}, note=[Accessed: 05-May-2025 ]}

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@online{reference.wolfram_2025_netevaluationmode, organization={Wolfram Research}, title={NetEvaluationMode}, year={2017}, url={https://reference.wolfram.com/language/ref/NetEvaluationMode.html}, note=[Accessed: 05-May-2025 ]}